Gout patients commonly present with nephrolithiasis. The development of renal calculi in patients with gout is primarily related to high levels of uric acid. The ionized forms of uric acid form salts like monosodium urate, disodium urate, or potassium urate (Bardin et al., 2021). Sodium is the main cation in the extracellular fluid. Urine acidifies along the renal tubules, causing a portion of urate to convert to uric acid. The solubility of uric acid in an aqueous solution is lesser than that of urate, but the saturation increases markedly with the increase in the pH value of urine (Bardin et al., 2021). Gout patients with long-term high uric acid levels have increased urinary uric acid concentration and form crystals after surpassing the solubility, which gradually enlarges to shape calculus.
Bardin, T., Nguyen, Q. D., Tran, K. M., Le, N. H., Do, M. D., Richette, P., Letavernier, E., Correas, J. M., & Resche-Rigon, M. (2021). A cross-sectional study of 502 patients found a diffuse hyperechoic kidney medulla pattern in patients with severe gout. Kidney international, 99(1), 218–226. https://doi.org/10.1016/j.kint.2020.08.024
Jia, E., Zhu, H., Geng, H., Wang, Y., Zhong, L., Liu, S., Lin, F., & Zhang, J. (2021). Effect of alkalized urine on renal calculi in patients with gout: a protocol for a placebo-controlled, double-blinded randomized controlled trial. Trials, 22(1), 743. https://doi.org/10.1186/s13063-021-05721-8